Self-locking joint for reinforced concrete pile sections

ABSTRACT

Two pile sections are joined together by interfitting means in their opposed ends. One pile has a plurality of lock bars ( 7   a ) extending substantially perpendicular to the end plate ( 3   a ), comprised of notches ( 14   a,    14   b ) formed periphery at the lower portion ( 14 ). The other pile has a plurality of lock sockets ( 7   b ) mounted substantially perpendicular to the end plate ( 3   b ), comprised flaps ( 13   a,    13   b ) within the cavity, formed from its opposed side walls and bending towards the axis of the lock socket cavity. When in splicing operation of the pile sections ( 1   a,    1   b ), the lock bars ( 7   a ) are introduced into the lock sockets ( 7   b ). The locking bar ( 7   a ) then prised in between the flaps ( 13   a,    13   b ) forcing them apart while the flaps ( 13   a,    13   b ) still maintain its clamping force. The notches ( 14   a,    14   b ) of the lock bars ( 7   a ) then engaged with lower the edges ( 15 ) of the flaps ( 13   a,    13   b ) thus locking the piles together.

TECHNICAL FIELD

The present invention relates to joints for concrete piles, methods for making concrete pile joints, and methods for joining concrete piles using those joints.

BACKGROUND ART

The most common pile used in many parts of the world, is the pre-cast reinforced concrete pile. Because of manufacturing, structural, transportation, installation, and other limitations associated with concrete piles, the length of the piles is often limited to a pre-determined length. Depending on the situation, it is often necessary to join, or splice, two piles end-to-end at a construction site when an individual pile section is not long enough for a particular application.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a reinforced concrete pile joint that is stiff, fast and economical while able to perform in utmost integrity under the most severe driving conditions, having a resulting joint providing flexural strength equal to that of the pile itself.

Joints have also been proposed that involve welding. However, these are relatively time consuming during fabrication involving costly downtime on the piling machine. They also carry the inherent risk of damaging the adjacent concrete as a result of heat input.

Joints requiring bolts carry the risk of bolt loosening as a result of vibration during driving. Sleeved type joints have a very poor resistance to bending as well as tensile forces. Mechanical joints that required inserting locking pins are hazardous to workers safety as large heavy hammers are often used or locking pins may accidentally be misplaced or loosen during driving.

In accordance with the present invention, one part of the pile section consists of projecting bars peripheral to each corner of the pile's end plate that has a substantial planar surface that correspond to the end plate of the other pile section it is to be jointed. Lower pile section comprised of locking sockets positioned in alignment with the locking bars when engaged end to end such that the locking bars are introduced into the locking sockets. Each locking bar consists of latches formed on both sides that when passed through the flap structures formed from the opposed side walls of the socket to secure and clamp the two pile tightly together.

U.S. Pat. No. 3,625,012 discloses a joint that is self-locking with interfitting means in their opposed ends. One end consist of a rod whose end is cut and projecting from it.

FIG. 9 of that patent, the wedge can be easily reversed by driving it back out of the key hole. The other pile has a tube embedded therein and when the rod is laced in the tube and as the pile is driven, the cut end is forced by a wedge into the flare of the tube, thus locking the piles together. However, the wedge can be easily reversed by driving it back out of the tube or loosen by the friction of the surrounding soil of the piles.

U.S. Pat. No. 3,884,589 discloses an exemplary locking joint for concrete piles having joined sections. The facing end surfaces of the sections to be joined are made of metal and have outwardly projecting pins and/or openings arranged therein, the openings communicating with the pin receiving spaces to receive the pin from a next pile section. The pin receiving spaces have metal walls and each pin has a transverse hole there through to receive a wedge device to be inserted through the hole in the pin through a bore projecting through the side of the pile section into which the pin is inserted, thereby to hold the ends of the pile sections in firm abutting relationship as previously described. The locking joint is mainly characterized in that the wedge device is held in locking position in the bore and in the transversally extending hole through the pin by locking means located in the bore adjacent the side surface of the pile section and on the wedge device itself.

U.S. Pat. No. 5,032,041 discloses a joining device for concrete piles having a “through-going cavity” (9) that traverses the width of the concrete pile and that allows one to insert a wedge (13) to secure two concrete pile ends together. As shown in U.S. Pat. No. 4,009,550 discloses a concrete pile joint box that is square- or box-shaped, illustrating what many concrete pile joints look like today.

U.S. Pat. No. 3,313,560 discloses a pre-tensioning wire anchoring system for concrete pre-compressed structures (concrete pipes are illustrated), and teaches using a flat socket member adapted to being placed at the end of a concrete form, the socket member having multiple spaced-apart through holes for insertion of a tensioning wire.

EP 1,288,382 discloses a joint for joining reinforced concrete pillars together, and requires that the projecting locking part have an annular groove, a connecting element that includes an annular groove, and a spring-like locking element which locks in the two grooves.

Prior art concrete piles use concrete anchor bars to provide a means to attach and/or align joints. However, anchor bars of that type are not suitable for precision component purposes. It is not uncommon to observe wet, muddy, and icy conditions at construction sites where concrete piles are used. Because concrete piles are often placed directly on the ground before use at a site, the transverse holes for the locking pins often become clogged with debris, ice, mud, pebbles, etc. However, if a straight path is present to the other side, the debris can simply be pressed through. Ice is a particular concern for concrete piles, as mentioned above, because the spliced sections often become unstable. Therefore, pin-receiving tubes that extend straight through from one side of the pile to the other present a significant prevention in lost resources due to unusable or damages to concrete piles. The aforementioned prior art pile joints and methods of joining piles fail to address those, and other known problems associated with typical concrete piles.

With those and other objects, advantages and features of the invention that may become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several drawings attached herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing showing an axonometric view of the splicing ends of two reinforced concrete piles each with a compatible joint according to the present invention;

FIG. 2 is a schematic drawing showing a partial cross-sectional view of two compatible joints in a pre-connecting position according to the present invention;

FIG. 3 is a schematic drawing showing a partial cross-sectional view of the ends of two joined reinforced concrete piles with one of the compatible joints interconnected according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Several preferred embodiments of the invention are described for illustrative purposes, it being understood that the invention may be embodied in other forms not specifically shown in the drawings.

Turning first to FIG. 1 , shown therein is a schematic drawing of an axonometric view of the splicing ends of two reinforced concrete piles 1 a, 1 b each with a compatible joint according to the present invention. The two reinforced concrete piles 1 a, 1 b are to be joined together with the pile ends tightly locked together. Piles 1 a, 1 b are primarily made of concrete, in addition to which they contain concrete reinforcement bars (“rebars”) 4 a.

FIG. 1 shows the structure of the joints 2 a, 2 b of the reinforced concrete piles 1 a, 1 b in more detail. Each of the joints 2 a, 2 b includes an end plate 3 a, 3 b, respectively, which may or may not include skirts 12 a, 12 b, as well as welded anchoring devices 4 a, 4 b, lock bars 7 a and lock sockets 7 b. A typical joint will include four lock bars 7 a spaced apart at the corners of the end plate 3 a of the upper extension pile 1 a and four lock sockets spaced apart at the corners of the other end plate 3 b of the below extended pile 1 b.

As shown in FIG. 1 , the joint 2 a of the upper reinforced concrete pile 1 a includes the end plate 3 a featuring lock bars 7 a for inserting into the lock sockets 7 b and forming, together with the skirt 12 a being slightly bent over, a box-like structure that is adapted to being positioned at the end of a rectangular or square concrete pile. The skirt 12 a may be created using a press, and are preferably about ⅜-inch in height around the entire periphery. They are non-structural components and are used for stiffness and casting. One of ordinary skill will appreciate that the end plates 3 a, 3 b of the present invention are not limited to being square- or box-shaped, but could encompass other shapes as well. Typical sizes for the end plate 3 a are well known in the industry by those skilled in the art. Fixed to the opposite sides (or corners) of the end plate 3 a, are the lock bars 7 a, aligned with the lock sockets 7 b in the end plate 3 b. The lock bars 8 a are preferable in square section casted in one piece with square or round shoulders 10 at the upper end which are wider than the body of the lock bars 8 a such that they can be slotted from the top of the end plate 3 a into slightly larger preformed square or round holes through the end plate 3 a and then welded onto the inner surface of the end plate 3 a with the reinforcement bars 4 a welded vertically on top at one end. Each of the lock sockets have a plastic sheath 9 inserted over it tight fitted to prevent concrete from entering into the socket cavity during casting of the joint to the reinforced concrete pile. The anchoring devices 4 a are fixed to the lock bar 7 a by welding or with threads. Two arrow indicators 10 a, 10 b stamped on the joint skirt 12 a, 12 b, act as a position guide for the male and female components of the joint to assist in correctly positioning the lock bars 7 a in relation to the lock sockets 7 b.

Although not shown in FIG. 1 , the lock bars 7 a and lock sockets 7 b can be placed on the same sides or at opposite corners of the respective end plates 3 a, 3 b.

As discussed previously, it is important to use economical materials in the manufacture of the joints 2 a, 2 b. To make the least expensive end plates 3 a, 3 b as possible, they are essentially a non-structural component of the joints 2 a, 2 b. Their main role is for alignment of the locking assemblies such as the lock bars 7 a and lock sockets 7 b. However, lower cost end plates 3 a, 3 b tend to have worse tolerances across the surface. However the tensile strength of the lock bars 7 a which are to be engaged with the lock sockets 7 b to splice the pile segments together must be of sufficient strength and preferably be made of material such as carbon steel above 800 MPa.

Turning now to FIG. 2 , shown therein is a schematic drawing of a partial cross-sectional view of two compatible joints 2 a, 2 b in a pre-connected or pre-spliced position according to the present invention. Extending through the end plate 3 a, there is attached to the upper pile a lock bar 7 a, to which the generally corresponding aligned lock socket 7 b are situated. FIG. 2 also shows the relative dimensions of the joints 1 a, 1 b indicated by alphanumeric symbols 10 a and 10 b, which are measured from the adjoining surfaces of the respective piles 1 a, 1 b. FIG. 2 shows that the dimension 10 a in the lock socket 7 a, and the dimension 10 b in the lock bar 5 b, can be machined highly accurately to the required size in order to ensure adequate tightness of the splice. This provides optimum tightness because the dimension 10 a, in a preferred embodiment of the invention, is a few tenths of a millimetre greater than the dimension 10 b, precisely engaging the two piles when joined together, which creates a very tight splice that is difficult to detect using traditional dynamic pile testing techniques, as previously described. The dimensions are important for the proper in-service performance of the lock socket 7 a and the lock bar 7 b. The actual dimensions 10 a, 10 b for specific applications can be ascertained by experimentation.

FIG. 2 also shows that the splicing half 2 a of the upper pile 1 a includes a protective plastic sheath 11 to prevent the ingress of concrete into the lock sockets 7 b during casting. Additionally, FIG. 2 shows that the lock bars 7 a, comprised notches 14 a, 14 b sized to the width of the flaps 13 a, 13 b formed from the side walls of the lock sockets 7 b by laser cutting through the sockets 7 b leaving the top side to attach to the flaps 15 a, 15 b and therefore when bend into the sockets 7 b, the flaps 13 a, 13 b from the opposite sides formed into a clamp like structure. When the two segments of the pile 1 a, 1 b are jointed end to end, the lock bars 7 a shall be introduce into the sockets 7 b and the tip of the lock bars 7 a shall press through the flaps 13 a, 13 b and prised it open. The lower edges 15 of the flaps 13 a, 13 b shall then clamp tightly onto the notches 14 a, 14 b of the lock bars 7 a when they reach the notches formed on the lock bars 7 a to form a stiff splice. The width of the flaps 13 a, 13 b must correspond to the width of the notches 14 a, 14 b to form a splice that is able to provide full surface contact to create maximum tensile and compressive strength of high integrity even under very harsh driving condition. The tip 14 of the lock bars 7 a is square conical for easier entry when introduced into the openings 6 formed through the end plate 3 b that are aligned to the socket 7 b mounted directly below which is slightly larger than the tip 14 of the lock bar 7 a.

Turning now to FIG. 3 , shown therein is a schematic drawing of a partial cross-sectional view of the ends of two joined reinforced concrete piles 1 a, 1 b (i.e., a splice) with the compatible joints 2 a, 2 b interconnected according to the present invention using the lock bars 7 a and the lock sockets 7 b. The lengths of the four locking bars 7 a measuring from the base of the end plate 3 a is slightly longer by a 10^(th) of a millimetre to one millimetre so as to ensure that the engagement of the lower edges 15 of the flaps 13 a, 13 b within the lock sockets 7 b shall precisely clamp onto the notches 14 a, 14 b of the lock bars 7 a to form a stiff joint when pile sections 1 a, 1 b are jointed together end to orientation.

Although certain presently preferred embodiments of the disclosed invention have been specifically described herein, it will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the various embodiments shown and described herein may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law. 

I claim:
 1. A joint for a concrete pile section comprising: a first end plate for connecting to the concrete pile; a plurality of spaced apart lock bars 7 a attached to and extending substantially perpendicular to the first pile section 1 a; a plurality of spaced apart lock sockets 7 b attached to and extending substantially perpendicular to the end plate of pile section 1 b, wherein each of the plurality of lock sockets 7 b has a cavity portion which are axially aligned with the lock bars 7 a when in locked position; notches 14 a, 14 b formed on the opposed sides of lock bars 7 a engaged with the lower edges 15 of the flaps 13 a, 13 b thus locking the two pile sections together.
 2. The joint according to claim 1, wherein a portion of the lock bars 7 a extends a distance into one of the lock sockets 7 b.
 3. The joint according to claim 1, wherein the lock bars 7 a comprise notches 14 a, 14 b formed periphery to the lower end 14 in alignment with one side of the opposite side walls.
 4. The joint according to claim 1, wherein the lock sockets 7 b comprise flaps 13 a, 13 b formed from the two opposite sides of the walls of the lock sockets 7 b and bending axially toward the axis of the lock socket cavity.
 5. The joint according to claim 1, further comprising a step edge formed circumferentially at the insertion openings 6 of at least four lock bars 7 a where they attach to the first end plate.
 6. The joint according to claim 1, further comprising at least one anchoring device attached to at least one of the plurality of lock bars 7 a and at least one of the plurality of lock sockets 7 b, wherein at least one anchoring device extends substantially perpendicular to the end plates 3 a, 3 b respectively.
 7. The joint according to claim 1, wherein the plurality of lock bars 7 a are square or cylindrical in cross-section.
 8. The joint according to claim 1, further comprising the notches 12 a, and 12 b of the locking bars 7 a slightly tilted away from the axis.
 9. The joint according to claim 7, wherein the notches 12 a, 12 b are formed at the opposed sides of the locking bars 7 a.
 10. The joint according to claim 1, wherein each of the plurality of the lock bars 7 a comprised a shoulder 10 formed at the upper end where the lock bars can be attached precisely to the end plate 3 a by slotting through a hole 7 formed through the end plate 3 a.
 11. The joint according to claim 1, wherein the distance 10 a of each of the plurality of locking bars 7 a from the larger external surface of the end plate 3 a to the notches 12 a, 12 b of the locking sockets 7 b shall at least be equal to the distance 10 b from the larger external surface of the end plate 3 b to the lower edges of the flaps 13 a, 13 b or slightly longer by a 10^(th) of a millimetre to a millimetre.
 12. The joint according to claim 1, further comprising a protective sheath 11 for inserting over the lock sockets 7 b to prevent the ingress of concrete into the socket cavity during casting.
 13. The joint according to claim 7, wherein locking bars 7 a and locking sockets 7 b are substantially square in cross-section.
 14. The joint according to claim 7, wherein each of the plurality of the notches 14 a, 14 b shall slightly be tilted away from the axis of the lock bar 7 a to be in synch with the angle of the lower edges 15 of the flaps 13 a, 13 b, when in locking position.
 15. The joint according to claim 1 comprise arrow indicators 17 a, 17 b shown on the visible side of the skirt 12 a, 12 b to assist in correct positioning of the joint components 2 a, 2 b in relation to one another.
 16. The joint according to claim 7 wherein locking bars 7 a are substantially cylindrical in cross-section throughout.
 17. The joint according to claim 1 wherein the lock sockets 7 b comprised at least a pair of flaps 13 a, 13 b formed on the opposed sides of the lock sockets 7 b and bending inward toward the axis of the lock socket cavity. 